Thousands of flights cancelled or delayed. Surgeries at hospitals postponed. Patient care disrupted across the globe. All because of one software bug. Last week, many Microsoft PC users reported that their computers were refusing to turn on, leading to a global IT outage that brought much of the world to a standstill.

What caused the outage?

Cybersecurity company CrowdStrike pushed an update to its widely used software 'Falcon' on the day. But, it turned out to be a faulty one. As it would be found out later, the update did not undergo adequate quality checks before deployment.

As such, even though the latest version was meant to make clients' systems more secure against hacking, a bug in the update files resulted in one of the most widespread tech outages in recent years for companies using Microsoft's Windows operating system.

As millions of Windows computers became inoperable, it led to significant disruptions across various sectors, especially those relying on strong IT infrastructure, ranging from airlines to banking to healthcare.

Before CrowdStrike deployed a fix for the issue, about 8.5 million Windows devices had been affected by the time globally.

Responses from CrowdStrike and Microsoft

In a statement, CrowdStrike said, "Due to a bug in the Content Validator, one of the two Template Instances passed validation despite containing problematic content data." It also admitted that its failure of an internal quality control mechanism allowed the problematic data to slip through the company's own safety checks.

Microsoft said it had fixed the underlying cause for the outage of its 365 apps and services including Teams and OneDrive, but residual impact was still affecting some services.

CrowdStrike offers "compensations"

CrowdStrike offered a $10 gift card to affected users as a gesture of goodwill. Many users received an email from CrowdStrike acknowledging the inconvenience and providing an Uber Eats voucher. However, some users reported receiving error messages stating that the gift card had been "cancelled by the issuing party and is no longer valid".

Financial losses due to the outage

In a report, global cyber insurer Parametrix revealed that one in four Fortune 500 companies faced service disruptions due to global outages. These disruptions, attributed to issues with CrowdStrike's software, resulted in a combined estimated loss of $5.4 billion. On average, affected companies faced losses of approximately $43.6 million each. Notably, all Fortune 500 airlines and about 75 percent of the top healthcare organisations and banks were impacted.